Naturally-occurring plant isoflavones are known to possess a wide range of fundamental biological effects on human cells including anti-oxidation and the up-regulation and down-regulation of a wide variety of enzymes and signal transduction mechanisms. Mitotic arrest and cytotoxicity of human cancer cells, increased capillary permeability, increased cellular adhesion, increased response of vascular smooth muscle cells to vaso-relaxants, and agonism of estrogen receptors, are just a few examples of the responses of animal cells to the biological effects of naturally-occurring isoflavonoids.
A range of therapeutic benefits as a result of these biological outcomes have been identified including the treatment and prevention of pre-menopausal symptoms such as pre-menstrual syndrome, endometriosis, uterine fibroids, hyperlipidaemia, cardiovascular disease, menopausal symptoms such as osteoporosis and senile dementia, alcoholism, benign prostatic hypertrophy, and cancers such as prostate, breast and large bowel carcinomas [see WO 93/23069; WO 96/10341; U.S. Pat. No. 5,424,331; JP 62-106017; JP 62-106016; U.S. Pat. No. 5,516,528; JP 62-106016A2; JP 62-106017A2; JP 61-246124; WO 98/50026; WO 99/43335; WO 00/49009; WO 00/644,438; WO 99/48496].
While over 700 different naturally occurring isoflavones are described, only a few are confirmed as having potential therapeutic benefits in animals including humans. These include daidzein, genistein, formononetin, biochanin and glycitein. These and all naturally occurring isoflavones are found in nature as the monomeric form either in a free state, or, more likely, bound to a carbohydrate moiety (glycoside). The isoflavone has to be separated from this moiety before it becomes biologically active.
A number of compounds with a structure related to naturally occurring plant isoflavones are also described as having biological properties with potential therapeutic benefit to animals including humans. These include compounds that are naturally occurring metabolites of plant isoflavones produced by bacterial fermentation by gut flora and embrace compounds such as equol and O-desmethylangolensin [WO 93/23069; WO 98/08503; WO 01/17986; WO 00/66576]. Also included in this group is the synthetic isoflavonoid ipriflavone, which is developed for the treatment of postmenopausal osteoporosis [WO 91/14429] and a wide range of synthetic isoflavonoid analogues [WO 98/08503].
Recently, some interest has been expressed in the biological properties of dimeric forms of isoflavonoids. Four forms of bis-isoflavones with the following structures are claimed to have 5-alpha-reductase inhibitory activity useful for the treatment of prostatomegaly [JP 9067362-A].

A C—C bridged bis-isoflavone dimer as shown below has also been described, but no biological activity or therapeutic benefit has been ascribed to it [Al-Maharik et al].

A requirement accordingly exists for new generation compounds that exhibit important pharmacological effects for use as prophylactics and in therapy.